the skinny on narrow boats

[dreamchaser]

is it true that a narrow boat requires more power my boat is 5ft at the lower transom corners by 18.5ft long

 

[Bob_VT]

Re: the skinny on narrow boats

It is related to displacement. 5' is narrow but it also depends on hull shape, material, power, salt or fresh water.... I have never heard that.

If it was true.... pontoon boats should be fast.

 

[Rancherlee]

Re: the skinny on narrow boats

To get on plain, YES. To go faster, NO.

 

[dreamchaser]

Re: the skinny on narrow boats

thks for the input ,,,, it just seems that a narrow boat would have less displacement .therefore needing more power ......

 

[steelespike]

Re: the skinny on narrow boats

It depends on what you are trying to plane.
A very small light boat like the ones the little kids race.
Probably barely 4 ft wide I think they plane with a 3 hp.
But with an adult nothing.
Same idea with larger boats and loads.My old Lonestar 15 ft.utility flew along pretty nice with a 25 and only one in it but would barely plane with 5 adults.My 18 ft Crestliner utility planed easily with the same motor with 5 people.Yet was probably slightly slower with only on aboard.
My point allways is buy the biggest boat you can afford.
There are 14ft utilities that are rated for about 700 lbs
and 15 hp and there are some rated for over 1,000 lbs and 25 or more hp.All these being bare bones utilities.
Yes a bigger footprint is generally easier to plane.
A bigger motor may solve the planing issue but a bigger boat is the better solution.

 

[River - Runner]

Re: the skinny on narrow boats

This is my experience of my narrow boat and for me it is the best. I bought it new. 1968 FD Alumacraft, 14 ft. semi-v, bare bones utility with soft round chine. 4 ft. wide at the transom (aqueduct transom). Boat only is 207 lbs.

I run it with a 4 hp., 25 hp. and 40 hp. The boat will plane with 4 hp., but me alone. The more weight you put in the boat the more hp. is needed to plane it and to go faster, because a narrow boat is always more in the water. A similar wider boat needs less hp. to do the same.

A boat should be dimensioned for how and where you intend to use it the most. Bigger may not be better. Boats are compromises, with many advantages and disadvantages of wide versus narrow and big versus small.

Some performance advantages of a narrow boat are a smoother ride and it will corner better than a wider boat of the same style. It is inherently a more rigid boat and has less stress put on it when used hard because of the narrow width. It will handle rough water better, track more solid and is less likely to kite in wind or when going airborne. After all is said,a narrow boat can be powered to go fast.

I owned bigger and wider boats but always go back to this boat. A compromise that suits me best and it's so easy to use.

Here are pics. and running the motors. It is rated for 40 hp. and a thrill to drive. The Mercury was the only brand that had a short shaft.

 

[Texasmark]

Re: the skinny on narrow boats

You can learn a lot about your setup just by looking at the wakes; in particular speed and weight differences in the engines.

We used to run a 33 John on that Alumacraft hull and it was real sweet.

Know you like it.

Mark

 

[River - Runner]

Re: the skinny on narrow boats

Very true about the visual with wakes and weights.

In reference to the pictured wakes, the 4 hp. and 25 hp. are running at WOT. The 40 hp. is at 2/3 throttle. To scary for me to take a picture like that at WOT with tiller steer. You need to give it your undivided attention.

In reference to motor weights. The 40 hp. motor weighs the same as the boat only. Which is good, because all weight is good running that motor.

 

[deejaycee_2000]

Re: the skinny on narrow boats

nice on River-runner, I agree with you .... the last 5 years I've been doing tests on exactly what you said here, my findings are as follows (although my tests are on inflatables) with a narrow 2,6 meter inflatable with a 15hp on I plane very slowely but have a good top end speed, with 2 people on, there is no planing it .... with a 30hp it planes better but with 2 people the weight makes the boat unstable ..... with 30hp on a transon extention with only me, it makes the narrow inflatable top heavy and doing 90 degree turns is out the qeustion and the boat will flip ... with the wider inflatable .... that distributes the weight more evenly, I get a faster plane and a more stable boat even at top speed and with a 90 degree turns ... and a much bigger oversized motor, I am currently working on a project where I used my tests as a guideline to build a lighter faster 4.2 meter racing inflatable that use to have a max hp of 50hp that will now be able to take a fully modified 85hp that will be about 115hp after modifications with tiller arm add on .... the kite effect you mention is what I rely on to give me more speed as the boat runs in about 20cm of water with only the prop and a small section of the highjackers in the water .... although I do disagree with what you said about rough water, I have flipped my narrow inflatable more in the rough water than my wider boats, as I can manuvre the wider ones with less effort than the narrow in the rough waters ..... what speed do you get with your 40hp on at WOT?

 

[DJ]

Re: the skinny on narrow boats

Look at the old wood boats of yesteryear. They were heavy, long and narrow.

They were long and narrow because they did not have allot of HP to work with back then. Even marinized auto engines were pretty low HP compared to today.

Long hulls allowed them to stay on plane with a minimum of power and at slower speeds.

 

[River - Runner]

Re: the skinny on narrow boats

deejaycee, When I said "It will handle rough water better", I am comparing to similar but wider boats. These boats are light. The wider boat pounds on choppy waters compared to a narrow boat and in large roller wakes the wide boat comes down harder. Also when weather conditions are so bad as to travel slow, it can take the large waves better that some bigger heavier boats. This boat doesn't fight the waves and I stay dry. Also stay dry when hit from the side by the waves. A narrow boat responds quicker than a more stable wide boat. There is a big difference between a round (soft) chine and square (hard) chine in boat performance. With advantages and disadvantages with both.

I don't know the speed with the 40 hp. motor on. My dealer rigged the boat with the 40 hp. and had it set up for 50 mph. We could not drive it a WOT. I had to slow it down with a different prop and weight for safety. It is as fast as I want to go.

I do remember some of your previous posts with inflatables and that picture when you are airborne. You must have a need for speed! Take care!

Kiting is my worst fear. When coming down in a different direction, if your lucky on it's bottom, the narrow boat won't slide like a wide boat and will flip easier. I've been there a couple of times and thrown to the floor, but didn't loose it. I was just lucky.

 

[deejaycee_2000]

Re: the skinny on narrow boats

oh I see, I geuss whe are on the same page, I just misunderstood a bit ....

I definately have a need for speed ..... the faster the better ...... hahaha

 

[dreamchaser]

Re: the skinny on narrow boats

phew...... thks all for ur input ....lots of diff opinions goin round .....lol ...im of the opinion that a narrow boat requires more power if compared to a same size and weighted wider boat ...thinkin bout those offshore race boats big power but long and narrow .and there rough water handlin comes to my mind . I have to agree with R Runner sayin that there good in rough water......".well this hull" ........ as i been out lots of times with other bigger boats,,, and the same size as mine and they cant keep up in the rough ....Wish i could strap on 2 115,s!!!